The present invention is applicable to any kind of machine, in particular to agricultural machines, such as balers. As is generally known, a baler is a machine which picks up from the ground crop material that has previously been cut, windrowed or swathed, and forms the crop material into round or square bales. The workings of the baler, that is to say the internal machinery that forms the bales, will not be described herein as they are not of particular relevance to the present invention and as their construction is well documented in the prior art. It suffices for the present invention to appreciate that the workings of the baler have many moveable parts which pose a safety hazard if left exposed to the operator while the baler is in operation.
The baler derives its power from a power take off (PTO) shaft of a tractor. To ensure smooth operation of the baler, its drive incorporates a large flywheel that is connected to the PTO shaft by an overrunning, or one-way, clutch. On account of this clutch, even when the tractor engine is stopped, it is possible for the flywheel of the baler to continue rotating. Because of this ability of the flywheel and the workings of the baler to continue moving even after the tractor engine has been stopped, it is known to provide a manually operable brake to cease rotation of the flywheel so that servicing work may be carried out safely on the baler. The brake may for example take the form of a brake band that is anchored at one end to the frame of the baler, passes partly around the circumference of the flywheel and is connected at its other end to a toggle mechanism. An actuator or handle may act on the toggle mechanism to apply and release the brake.
In normal use, the moveable parts of the baler are covered by access panels. The flywheel is covered by a hinged hood and other moveable parts of the baler are protected by hinged access panels. When the baler needs attention, for example if a blockage has occurred, an operator stops the tractor and descends from the tractor cab. Next, the flywheel brake should be applied to bring all the moving parts of the baler to a standstill and only when it is safe does the operator raise the hood or open one of the side doors to provide access to the workings of the baler.
A problem with existing balers is that nothing prevents an operator from inadvertently or intentionally omitting to apply the flywheel brake before opening one of the access panels, thus exposing him to a risk of severe injury. It will be clear that this problem would apply to any agricultural machine having workings driven from the PTO shaft of a tractor by way of a flywheel that is capable of overrunning.
In WO2011/018456 solutions to this safety problem are provided; however, those proposed solutions are rather complex and hence costly. Further the solution focuses on one particular aspect of the problem, being the door opening and continued rotation of the flywheel while also other aspects such as door instability, operator ergonomics and effects on the entire machine frame should be looked at.